Such an antenna core is known, for example, from U.S. Pat. No. 5,567,537, in which the use of specific amorphous and nanocrystalline alloys is described for production of so-called thin film antennas. Among other things, retention of soft magnetic and physical properties before and after a bending load is discussed there as criterion for good applicability of such thin film antennas, for example, in chip cards. In particular, it is demonstrated that such thin film antennas exhibit no cracks after bending loads, in contrast to ferrite rods.